Bozeman, Mont. — In June 2007, Dennis VanDenbos, a high school science teacher from Lander, Wyo., was attending an education conference at the Jackson Lake Lodge in Wyoming’s Grand Teton National Park.

Mr. VanDenbos set out walking one morning and, unbeknown to him, he spooked a mother grizzly bear and three cubs that were feeding on an elk calf they had just killed. Acting in defense of her offspring, the mother sprang from cover and set upon the human intruder.

In a single freeze-frame moment of clarity, VanDenbos saw the angry mother, her neck fur standing on end, and beside her three smaller bear shapes. Backpedaling, he yelled and waved his arms to try to make himself look bigger. Unfortunately, in retreat, he stumbled. As VanDenbos tried to stand up, he was eye level with the parent.

“I dove straight down and pulled my arms over my head,” he said later, and braced for the worst. “She came and bit me in the back as I played dead. I don’t know why, but I had the sense it was just a warning.”

The sharp nip was followed by a more powerful clamping of teeth into his backside. VanDenbos, now pinned to the ground, felt a bear paw on his left calf, and then he was stung by another bite in his left rump.

A moment later, he heard a loud human voice. The weight of the paw that had been resting on his body suddenly lifted. As it turned out, a cook and a wrangler who guides horseback rides had spied the huddle of bears. When they yelled, the mother and cubs ambled away.

“I didn’t get a sense, based on her actions, that she wanted to hurt me, or eat me,” VanDenbos said.

Few would have been surprised if the arriving park rangers had shot and killed the bear family. But, as VanDenbos was loaded in a truck and taken for medical care, he radioed back to the rangers to say that he had inadvertently provoked the attack and wanted no harm to come to the bears. They were spared.

Something remarkable happened in the aftermath of the encounter: The grizzly matriarch, already popular with locals in rural Wyoming, became a bona fide global icon – the most famous wild bear in the world.

Given the identity “399” by scientists with the federal Interagency Grizzly Bear Study Team – a highly respected mammal research group – she has also had her wanderings tracked in another way. For most of the past decade, 399 and several litters of cubs have been closely followed by noted American wildlife photographer Thomas Mangelsen. The best of his quarter million frames are assembled in a new book, “Grizzlies of Pilgrim Creek.”

“There were some grizzlies in Yellowstone, but typically I had to leave the region and head to Alaska if I wanted to see brown bears,” he says. “When 399 showed up, it changed everything....”

The ascent and inevitable struggles of 399 and her offspring are in many ways representative of all grizzlies in the modern American West. Theirs is a tale of one of the most successful wildlife recovery programs in the world – a resurrection that has taken the bear from the brink of extinction in the Lower 48 to a population of as many as 1,000 in the Greater Yellowstone region, which includes parts of Wyoming, Idaho, and Montana, as well as an equal number in ecosystems around Montana’s Glacier National Park and farther to the west.

As their numbers grow, grizzlies face daunting pressures – from poachers, big-game hunters killing them in self-defense, crowds of admiring tourists, dwindling food supplies, and humanity’s increasing development of the wilds.

Now comes a pivotal moment in the fortune of the iconic animal. The US Fish and Wildlife Service, official federal custodian of imperiled species, is poised to announce that grizzlies in Greater Yellowstone will be removed from protection under the Endangered Species Act.

Should it happen, management authority will be handed over to Wyoming, Montana, and Idaho. Those states already have made clear their intention to revive sport hunting of grizzlies, leaving many to worry that 399 could end up in someone’s gun sights – no differently than what happened last summer with the killing of Cecil the lion by a Minnesota bow hunter in Zimbabwe, which ignited an international firestorm.

Indeed, a ferocious debate is swirling about whether the population of grizzlies has revived to the point at which “delisting” them is a good idea. Some environmentalists question if states can be trusted to oversee the bear since it was under their watch historically that bears almost disappeared. Proponents of delisting believe they can – and should. The next steps here are being closely watched around the world, especially in regions trying to revive populations of imperiled tigers, lions, jaguars, and other charismatic predators.

• • •

For some of us, no matter where we call home, the Latin scientific name for the animal tells us all we need to know about a notorious beast that has evolved for a million years. Ursus arctos horribilis. Literal translation: the horrible bear.

Feeding our worst primitive fears, grizzlies, it is said, can outsprint a horse over short distances; their canine fangs, trademark thrasher claws, and formidable jaws are capable of crushing the femur of a one-ton bison; and these hulking brutes pack temperaments prone to easy agitation, unpredictability, and lethal aggression.

We love to make ourselves scared thinking about grizzlies, just contemplating the paralyzing prospect: Should you run when a grizzly approaches or collapse to the ground, curl into the fetal position, and play dead? Answer: It depends.

Did I mention that those frightening claws a grizzly flaunts on its front paws function, in fact, as tools for digging plants, worms, and insects, and excavating ground squirrels from subterranean warrens – not as nightmarish talons?

Urban legends have always stalked the grizzly. Native Americans in the arcs of their ancient oral traditions ascribed mystical, reverential powers to “the Great Bear.” Members of the Lewis and Clark Expedition noted one of their first encounters with the shoulder-humped bruin as they were headed westward up the Missouri River in 1805. On May 5, Capt. William Clark scrawled, “In the evening we saw a Brown or Grisley beare on a sand beech, I went out with one man Geo Drewyer & Killed the bear, which was verry large and a turrible looking animal, which we found verry hard to kill we Shot ten Balls into him before we killed him, & 5 of those Balls through his lights....”

For the next 170 years, until they became protected in 1975, grizzlies would dwindle in number from 50,000 to only a few hundred.

• • •

Hiking in grizzly country, living in it, comes with the possibility that something bad could happen. But the likelihood of being mauled by a bear is incredibly low.

Last summer, a hiker was killed by a mother grizzly in Yellowstone, prompting park officials to euthanize the bear and send her cubs to the zoo in Toledo, Ohio. Yellowstone experts are often asked just how risky it is to traverse grizzly country. Their answer: Over the past 30 years, some 95 million people have visited the national park, and during that time 44 people were injured by bears.

For park visitors, the chances of being injured by a bear are approximately 1 in 2.1 million, the chances of being fatally mauled far less. As of late 2015, only eight people have been killed by bears in Yellowstone since the park was created in 1872.

“More people in the park have died from drowning, burns (after falling into thermal pools), and suicide than have been killed by bears,” a park synopsis states. “To put it in perspective, the probability of being killed by a bear in the park is only slightly higher than the probability of being struck and killed by lightning.”

Mr. Mangelsen is careful. He has never been attacked, and even though he is familiar to 399, he refuses, for ethical and safety reasons, to invade her space.

Photographers, the good ones anyway, have a sixth sense for identifying the profundity of moments. Steven Fuller’s camera has helped him reflect on these risks. The landscape photographer and friend of Mangelsen has lived in the center of Yellowstone for nearly 45 years and is the winter caretaker at Canyon Village. Grizzly recovery has happened all around him.

I was once visiting him at his historical old cottage above the Grand Canyon of the Yellowstone. As we were exiting his back door, an adult grizzly suddenly sauntered past us, literally at arm’s length. The bear’s only acknowledgment was a quiver of his ear, as if to say, “Hello, nice night, isn’t it? If I wanted to take you, well, you know, I could but I have no interest in messing with you.”

• • •

After VanDenbos’s encounter with 399, millions of people became aware of her and the cubs. Americans and global travelers flocked to Grand Teton hoping to catch sight of the clan. Because of 399’s skill and comfort level in navigating the developed front country, which made her more visible to visitors, Grand Teton began to occupy a vaunted new place on the grizzly bear map.

Yet the bear’s star status created new dangers, too. “Bear jams” started to become commonplace, with cars backed up for miles whenever the mother was seen along highways. Tourists would haphazardly hit the brakes, fling open doors, and sprint with unbridled excitement to within close proximity of the sow and cubs. Not a good idea, given the reputation of grizzly mothers for being zealously protective. But 399 kept her cool.

“Around her are all these things going on – people moving in and out of her space, conveying different kinds of messages through body language,” says biologist Susan Clark, a professor of environmental studies at Yale University who spends summers in Jackson Hole, Wyo., at a wildlife research center. “There are smells of human foods drifting in the breeze. There are vehicles moving at various speeds.... I see an animal that exhibited remarkable composure in showing her cubs how to move through the chaos.”

Often, park rangers would have to rush in to manage the mobs. In many instances, before they took control, the only thing that prevented people from getting too close was Mangelsen and other wildlife photographers telling tourists to stay back. It didn’t take long for the most ardent bear advocates, including a special citizen unit created by Grand Teton National Park, to realize that 399 was in perpetual danger.

“It was a miracle in those early years that she stayed alive, that she kept her cool and did not feel threatened as she and the cubs moved around cars and people...,” Mangelsen says.

Yet other perils were stalking 399’s clan as well.

• • •

The current boundaries of Grand Teton National Park were established in 1950. Part of the deal Wyoming lawmakers made with Congress when it expanded the park was ensuring that traditional elk hunting would remain to help reduce the elk herd. It is a cultural artifact as much as anything else.

Yet the park’s elk hunt often puts bruins and humans in perilous proximity. Hunters leave behind “gut piles” after they’ve dressed their elk in the field, and the remains inevitably attract bears.

Every year the hunt brings stories of another spectacle. Mangelsen recalls an episode in the fall of 2007 that galvanized his views about what he calls the “strange absurdity” of the park hunt. On Oct. 15, a group of people – mainly Mangelsen and some hunters – were gathered at Teton Point Overlook near the Snake River. A hundred yards below in the rolling sagebrush were 399 and her three cubs hunkered over a bull elk carcass. “It was glorious and yet, in the context of the danger all around, kind of surreal,” Mangelsen says.

He and Sue Cedarholm, another wildlife photographer, returned the next morning to find the bear family lying near the carcass, full of meat. Mangelsen and Ms. Cedarholm, to their horror, counted 18 hunters waiting for migrating elk. They were oblivious to the fact that 399 and her brood were nearby.

One of the hunters remarked openly that his buddy had been the one who mistakenly – and illegally – killed the bull elk a day earlier. With only a tag for a cow elk, the hunter left the wapiti behind to rot in order to avoid being ticketed. The man next to Mangelsen said, “The problem with this park is that there are just too many damn grizzlies interrupting our hunt.”

Mangelsen didn’t react. While talking, the man pointed to two more orange-clad hunters below the turnout. They were on a collision course with the four bears. Mangelsen and the man yelled to warn the others. Still, the hunters’ presence startled 399 and her family. The bears jumped up and bolted toward another row of hunters along the river.

Fortunately, nothing happened that day. Perusing for elk in the opposite direction, none of the hunters saw the bears coming; 399 could not see them either because of the rolling terrain. “Fortunately for everyone, she miraculously chose a path between the gantlet of hunters,” Mangelsen says.

Mangelsen and a growing number of other people believe the park hunt has outlived its original purpose. “The park has changed, society has changed, values have changed, and grizzlies, one of the rarest creatures in the Lower 48, have a much-deserved home in Grand Teton, when seven decades ago, they didn’t,” Mangelsen says.

Such outspokenness has given Mangelsen a reputation for being, as one park official put it, a “hell-raiser.”

• • •

The elk hunt raises another question. For decades, the notion has been advanced that when bears hear gunshots they equate it with the ringing of a dinner bell and move in the direction of the noise.

They allegedly do it because they sometimes get a food reward in the form of an elk, moose, or deer that has been dropped by a hunter. According to Mark Haroldson and Frank Van Manen of the Interagency Grizzly Bear Study Team, it sounds plausible but hasn’t been documented scientifically as an irrefutable cause and effect.

Cuing bears to kills is not just the explosion of gunpowder but the smell that is released into the wind when a hunter creates a gut pile. It’s a bear’s gifted nose, not its ears, that leads the way. “The olfactory senses of a bear are so incredible that it’s something we as humans cannot come close to appreciating,” Mr. Van Manen says.

Research has shown that the likelihood of Yellowstone bears moving outside the park during early elk-hunting season is two to four times higher, a correlation that some link to the availability of elk carcasses.

A number of hunting guides whom I’ve known over the years are salt of the earth, proud to have grizzlies and wolves on the landscape. Jackson Hole guide Forest Stearns, owner of A+ Outfitters, doesn’t want harm to come to 399, but he doesn’t want the park hunt shut down either.

“When I first started guiding hunting trips in the mid-1970s, there were a few grizzlies around Jackson Hole, but they were the exception rather than the rule,” he says. “Now we have them coming out of our ears everywhere. The recovery deal has worked very well.”

Mr. Stearns requires that every hunting party undergo an orientation on how to use bear spray – which studies show is more reliable than trying to fell a charging bear with bullets – and how to be vigilantly aware in bear country. Stearns emphasizes the regulations that demand quickly field-dressing an animal, moving it away from a gut pile, packing out the meat, and realizing that grizzlies, according to his own experience, do move toward gun blasts. “Coexistence between people and bears is a work in progress,” he said. “We, in this day and age, have to be a lot more on our toes.”

• • •

The main argument invoked to delist grizzlies is that the population has recovered in the core habitat of Greater Yellowstone (best guess is at least 700 bears). One sign of this: Grizzlies are showing up in places outside the area where they haven’t been seen in a century.

But this fall, researchers acknowledged that the population growth rate in the center of bear range has slowed or is flat. At the same time, some scientists believe that a decline in key foods the bears eat could imperil the stability of the population.

Grizzlies are omnivores and opportunistic feeders. As a recent study of foods by Yellowstone senior bear manager Kerry Gunther shows, they eat more than 200 different natural edibles. However, not everything in the pantry is equal.

Mangelsen attended a lecture given by David Mattson in Jackson Hole on bear foods. Dr. Mattson is an adjunct professor at Yale University who spent much of his career doing research for the US Geological Survey and the grizzly study team.

Put simply, Mattson said that a group of four fat-rich foods have, more than any other, powered the climb in bear numbers since the Yellowstone bruins were weaned off garbage from trash dumps several decades ago. These include the seeds from whitebark pine trees, army cutworm moths, cutthroat trout spawning in the streamside tributaries of Yellowstone Lake, and meat (acquired by killing elk, moose, and deer, or scavenging the carcasses of dead animals).

Yet the whitebark pine forests of Greater Yellowstone have been under attack by a fungus called blister rust and mountain pine beetles. Roughly 8 of every 10 whitebark trees that existed 25 years ago have been killed. The illegal introduction of nonnative lake trout into Yellowstone Lake has resulted in an alarming crash of cutthroat trout in streams where they are easy for bears to catch.

Army cutworm moths are, for now, stable, and attracting huge numbers of bears to wildflowers in the high country. But their future is uncertain because of possible exposure to pesticides and the threat global warming poses to the flowers. Finally, ungulate meat is available in elk but in far fewer numbers than in the past because of more competition from wolves, lions, and people.

Mattson’s provocative contention is that, as these major bear foods disappear, it will lead to a hollowing out of the ecosystem’s ability to sustain larger bear numbers.

His narrative runs counter to the one advanced by delisting proponents as well as by many government bear managers. Part of their story line involves the suggestion that more grizzlies will need to be taken out of the population because they will become “conflict bears” – attacking livestock, inhabiting areas near towns, or acting aggressively toward humans.

But Mattson believes that more bears are showing up in the periphery of the ecosystem because they’re trying to find food that no longer exists in Greater Yellowstone.

“Grizzlies are notoriously slow to reproduce,” Mattson says. “And we also know from history that the difference between a rising or steady population and one that tumbles into decline can be higher mortality of female bears, by just a few percentage points, over a few years.”

Yet others, such as Dan Ashe, director of the US Fish and Wildlife Service, and Chris Servheen, the agency’s longtime bear recovery coordinator, say the grizzly population has unequivocally recovered to the point where it should be delisted. Even some conservationists, including Tom France and Hank Fischer of the National Wildlife Federation, think the population is stable enough to remove from protection. If it isn’t, they worry that critics of the Endangered Species Act will try to repeal the law altogether.

• • •

For Mangelsen, 2012 was filled with both inspiration and melancholy. After No. 610, one of 399’s original triplets, took on mothering duties for one of 399’s cubs, the other two demonstrated independence and strong personalities. Mangelsen and some friends named the brother and sister, now yearlings, Brownie and Ash so he could identify them.

On June 21, 2012, Brownie was viewed wandering along a roadside, attracting attention from passing motorists. In an incredible accident of the bears simply being in the wrong place at the wrong time, Brownie was run over by a car.

Later, in the fall of 2012, Grand Teton National Park and the state of Wyoming issued 725 elk hunting tags and the park again turned into a land mine. On Thanksgiving morning, Mangelsen got word that a grizzly had been shot and killed along the Snake River not far from where 610 and her cubs had claimed a carcass earlier and from where 399 had experienced a hair-raising encounter with hunters. He and Cedarholm rushed to the scene. They learned that it was a large adult male, the first grizzly killed in the park hunt. They didn’t know which one.

It happened while a father and his two sons were elk hunting. They had surprised a bear near an elk carcass in the woods. The father said he pulled out bear spray and emptied it into the grizzly, but the bear kept coming. The sons then opened fire and killed it with five shots.

The incident was classified as justified self-defense, though it was discovered that the can of bear spray had expired nine years earlier. It turned out that neither 399 nor 610 nor her offspring were the victim.

• • •

Bear managers usually try to give wayward grizzlies three strikes. In 2010, one of 399’s original triplets, No. 587, earned his first strike when he killed cattle in part of the Upper Green River system. His second offense came a short time later when he killed sheep. That led to him being trapped and transported back to Pilgrim Creek, his ancestral home. But he didn’t stay put.

The following year, in 2011, he killed cattle again. Strike 3. Ecologist Steve Cain, Grand Teton’s senior scientist, noted that he was good at killing prey. He had been taught well, after all, by 399.

Mr. Cain, who retired in 2014 but was a fan of 399 and family, had a hunch: 587 was a victim of bad timing. In early summer, the Upper Green River area had plenty of elk calves to feast upon, but after they grew bigger and were harder to catch, the bear likely shifted over to more docile fare – beef calves on public land grazing allotments.

On July 7, 2013, he was euthanized for chronic livestock depredation. He joined two other female grizzlies that were also killed for targeting cattle.

Bear defenders say it’s ironic that grazing nonnative cattle, being fed grass to fatten up and ultimately bound for the slaughterhouse, would take precedence over native grizzlies that are behaving as the predators they are. The state of Wyoming spent about $300,000 in 2014 resolving bear conflicts with wildlife and compensating ranchers for livestock losses. Since 2003, Wyoming has spent $1.6 million in reimbursing ranchers for animals killed by bears.

Both Mr. France and Mr. Fischer of the National Wildlife Federation recognize that cattle grazing represents a chronic hazard for grizzlies and wolves in Jackson Hole. Quietly, they have been working to broker solutions: buying ranchers out of public grazing allotments in Grand Teton National Park and Bridger-Teton National Forest, freeing up more safe terrain. It’s a move that many say has made a difference between grizzlies meeting heightened hostility.

“By paying ranchers a fair value to give up problematic allotments, we have solved a problem for both parties,” Fischer said.

• • •

Bonnie Rice of the Sierra Club speaks aloud about the topic no one wants to discuss. “Perhaps the biggest question is, should this majestic and rare animal – the ultimate symbol of our wild heritage that today occupies less than 2 percent of its historic range – be hunted for sport?”

Ms. Rice says “no” to delisting and hunting grizzlies. She makes clear that she’s not opposed to hunting big-game animals, such as elk, for meat. Just not grizzlies.

Americans have spent millions of dollars resuscitating grizzlies in Greater Yellowstone. It has been more than 40 years since they were last hunted in the West. Hunting grizzlies is not a deeply ingrained cultural tradition in contemporary society. Therefore, conservationists believe there is no compelling reason to hunt bears.

For 399 and 610 – because their response to humans is arguably more sophisticated and tolerant – their trusting nature of humans would, ironically, make them more vulnerable and perhaps the first to be killed. “Is that really what Wyoming would want to do with bears that are ambassadors for the most popular wildland destination in the state and Lower 48?” Mangelsen asks.

Further, some bear advocates argue that grizzlies are worth far more alive than dead. A study published in the Journal of Environmental Management indicates that grizzlies in Yellowstone alone contribute millions of dollars in economic value. Tourists would be willing to pay $41 in addition to the park entrance fee of $25 to see bears.

According to researchers, results indicate that if bears were no longer allowed to stay along roadside habitats, spending in the local economy by park visitors would decrease by about $10.1 million. Overall, nature tourism in the area, of which grizzlies and wolves are a marquee attraction, has been estimated at $1 billion a year.

• • •

The journey of 399 hasn’t ended. This summer the sow was seen in the company of male suitors, and if she survives another winter, she will likely emerge in spring 2016 as a 20-year-old mother with a new batch of cubs at her side.

These bears have alighted imaginations, debunked anachronistic myths, charmed their way into our own sense of place, and given us a better perspective on the value of rare species in a crowded human world. Yet reality forces us to look inward at ourselves.

Yes, 399’s bloodline remarkably contains 15 offspring – and counting – but it is sobering that over half, at least, have already perished from clashes of various kinds with people. In fact, after all this, 399 has barely begun biologically to replace herself. Meditate on that for a moment. Is that a prescription for recovery?

More information on “Grizzlies of Pilgrim Creek,” from which this article is adapted, can be found at mangelsen.com/grizzly.